The present invention relates to the art of inkjet printing and, more particularly, to a method of preventing the clogging of orifices without the necessity of automatic or manual wiping and capping thereof between print jobs.
As is well known in the art, inkjet printers include one or more printheads which eject ink through multiple orifices in an orifice plate to form the desired characters on the media on which printing takes place. The firing of the ink through the individual orifices of piezoelectric or thermal inkjet printheads is electrically controlled. Although the invention is primarily intended for use in fixed head printers, e.g. mail printers, the teachings of the invention are also applicable to other types of printers such as desk top printers and large format printer/plotters which use one or more printheads mounted on a movable carriage which traverses back and forth across the path of movement of the paper or other media on which printing is to take place. Typically, such high end printers employ automatic printhead servicing stations which include printhead wipers, caps, spittoons and other servicing components all located laterally of the media path to service the individual printheads and cap them from time to time between print jobs to prevent prolonged exposure of the printheads to the atmosphere with resultant drying of ink and clogging of the printhead orifices.
Current fixed head printers do not include separate printhead service stations due to the attendant cost and difficulties involved in accessing the printheads with servicing components. Print startup problems caused by clogging of the orifices of fixed head printers are thus very common. It is necessary for operators to remove the printheads for manual servicing such as cleaning of the orifice plates with water and cloth before starting a print job. This job is a comparatively dirty and undesirable one which is often postponed with resultant deterioration of the print quality. It is accordingly the primary objective of the present invention to provide a simple manner of automatically servicing the orifices of inkjet printheads without the necessity of manual intervention.
The present invention therefore provides a method of operating an inkjet printer comprising the steps of:
a) printing a desired pattern onto moving print media by ejecting printing fluid from a supply thereof in a desired pattern through orifices of an inkjet printhead;
b) terminating said printing onto said media;
c) periodically ejecting printing fluid from said supply through said orifices to periodically servicee said orifices until printing is to resume; and
d) resuming said printing by ejecting printing fluid from said supply through said orifices in a desired pattern onto said moving print media.